And not just if you take them off at the wrong time, either.
Fashion expert Alison Matthews David explains why the Hatter in Alice’s Adventures in Wonderland was “Mad.” She says, “Hatters used to work with highly toxic materials that led to mercury poisoning. Their symptoms were pallor, anemia, trembling and disorientation. It’s possible that Lewis Carroll, who grew up near a center of the hatting trade, would have seen people behaving as ‘mad as a hatter.'”